Starting and operating circuits for fluorescent lamps



Jan. 3, 1956 w. s. H. HAMILTON STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Filed Aug. 22, 1952 5 Sheets-Sheet 1 INVENIOR: W111i ELTTL 5 H -HELI'ILilEEI T1,

ATTORNEY.

STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Filed Aug. 22, 1952 Jan. 3, 1956 w. s. H. HAMILTON s Sheets-Sheet 2 INVENTOR: William-L5 -ILI-Iamfltnn ATTORNEY STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Filed Aug. 22, 1952 W. S. H. HAMILTON 3 Sheets-Sheet 3 ZNVENTOR: @5771 William 5 H Hamiltun a. BY

ATTORNEY United States Patent.

STARTING AN'D OPERATING CIRCUITS FOR FLUORESCENT LAlVIPS William S. H. Hamilton, Larchmont, N. Y.

Application August 22, 1952, Serial No. 305,790

8 Claims. (Cl. 315-100) This invention relates to certain new and useful improvements in starting and operating circuits for A. C. and D. C. fluorescent lamps, particularly long hot cathode A. C. fluorescent lamps, such as the 48", T-12 type, in which the filamentary electrodes have to be heated to cause the lamp to fire. Most of the commercial circuits for lamps of this type employ the glow switch type of starter which gives satisfactory results where the minimum cost is desired and where there are a considerable number of lamps connected in a group. The glow switch type of starter, however, is often uncertain and erratic in operation, as, while some starters of this type, when the line circuit is turned on, will at certain periods or under certain conditions of use, cause the filaments to glow almost immediately and the lamp to fire shortly thereafter, the same type of starters at other times will merely when first operated cause a momentary flicker in the filaments of the lamp followed by a long delay, during which the lamp is dark, before the starter operates again to close the circuit through the filaments so that the normal starting operation will commence. This erratic starter action is particularly objectionable in the use of single lamps in individual rooms or in locations where the lamps are subject to vibration.

These objections to the-use of fluorescent lamps with glow switch starters may be overcome by the use of a circuit such as shown in Fig. 6 of my prior application Serial No. 171,495, filed June 30, 1950, and divided there from and transferred to my application Serial No. 301,252, filed July 28, 1952, now Patent No. 2,703,375, in which circuit a starter of thermostatic switch type is used in conjunction with a controlling relay in such manner as to insure reliable and quick starting actions of a lamp in good order during the entire useful life, period of the lamp. The circuit originally shown in Fig. 6 of my aforesaid prior application Serial No. l71,495,'however, is basically open to the objection that when attempts are made to start a lamp which has reached the end of its useful life and will not fire, the starter and relay will cycle continuously until the lamp is removed from the circuit. This will cause annoying flashing of the lamp and arcing of the relay contacts which open and close, while the lamp refuses to fire, and also cause an objectionable noise due to repeated closing and opening of the relay and excessive wear on the parts involved. Y V

The object of the present invention is to provide means to overcome the stated objections to the use of lamp circuits employing a thermostatic type starter, such as those shown in my aforesaid prior application and other functionally equivalent circuits. The present invention provides for this purpose means for automatically locking out the starting arrangement, so that it cannot act, when the lamp is defective or has reached the end of its useful life period. v v

In the accompanying drawings I have shown certain new circuits for carrying the present invention into practical effect, in which drawings:

Figures 1, 2, 3, and 4 are diagrammatic views of different forms of circuits for operation of lamps on A. C.

and equipped with automatic starter lock-out arrangements embodying the invention.

Figures 5, 6, 7, 8 and 9 are similar views of forms of circuits for operation of lamps on either D. C. or A. C. equipped with automatic starter lock-out arrangements embodying the invention.

Referring now more particularly to the form of the invention shown in Fig. 1, 1 represents the gas containing envelope of the lamp having the filamentary electrodes 2 and 3, and 4 and 5 are line circuit conductors for supplying current from a suitable A. C. source to the lamp and starter elements located in a can or casing 10. These conductors are connected at the terminals B. W. to the terminal leads of the primary 6 of a reactor-transformer 7, which is thus connected across the line. From the secondary 8 of this reactor-transformer leads a feed conductor 9 which is connected to one end of the filament 2, from the other end of which extends a preheating circuit including conductors 11, 11 and 12, conductors 11', and 12 being coupled by the normally closed automatically reclosing switch member 13 of a relay, including a second switch member 14, and an actuating coil 15. A condenser 13' is placed across the switch member 13 to prevent arcing at the contacts when said switch member opens.

Conductor 12 leads from switch member 13 to the input end of the filament 3, the output end of which is connected to the operating circuit leads 25 and 15 leading to the line terminal 5, through the relay coil 15 which is thus connected in series with the filament 3. A second conductor 17 is connected to the conductor 11 and bypasses the switch 13 and is connected to the conductors 25, 15' at their junction by a cross conductor 16' having arranged therein a main starter heating element 16. In the conductor 17 is arranged a second or auxiliary starter heating element 18 which is electrically insulated from heating element 16except at their common junction point and is of high resistance compared with heater 16. Conductors 9, 11, 11 and 12 form parts of a preheating circuit for preheating the filaments. Conductors 9, 11 and 17 form parts of a lock-out or holding circuit which is short-circuited by the switch 13 when the latter is closed, and is set into action when the switch 13 opens and breaks the preheating circuit.

Conductors 19 and 20 are connected respectively at one end of the conductor 17 and to the terminal 5. Conductor 19 has arranged therein a reactance coil (or resistance) 21 and terminates at its opposite end in a contact 22. Conductor 20 is connected at itsjopposite end through the relay switch 14, conductor 23, .and thermostatic switch contact, or member, 24 with the conductor 17 and through conductor 16' and conductor 25 with the output end of the filament 3. Switch 14 normally connects the conductors 20 and 23, and thermostatic switch member 24 normally connects conductors 23 and25 to complete the preheating circuit through conductors 11 and 12 and heater 16,until the thermostatic switch member 24 moves out of engagement with conductor 23. As the relay coil 15 is arranged in the conductor 15' which is shunted across the switches 14 and 24 and between conductors 2i) and 25, the coil 15 is essentially short circuited as long as the thermostatic switch member 24 is normally closed to connect 23, 25.

Switch member 24 is adapted when heated to a certain degree or for a certain period of time by the heater 16 to break connection between the conductors 23, 17, 16 and 25 without engaging contact 22, thus connecting coil 15 into the circuit so that it may be energized by flow of current in the preheating circuit, to open both of its switches 13 and 14. When switch 24 is heated to a greater extent or for a sufiicient time by the conjoint action of heaters 16 and 18 it will be caused to engage contact 22 and connect coil 15 through conductor 19, reactor or resistor 21, conductor 17 with line conductor 5, thus causing the relay to remain in the position in which its contacts 13 and 14 are open. The thermostatic switch is preferably one which is relatively slow moving to the full open position and opens to different degrees under diflerent degrees of heat to perform the functions described.

In the operation of the circuit shown in Fig. 1 when starting, current flows from the secondary 8 of the reactor-transformer 7 through filament 2, relay switch 13, filament 3, starter heater 16, through the thermal element 24 in its downwardly closed position and through relay switch 14 to the line at 5. As soon as the thermal element 24 is heated enough by heater '16 to move out of engagement with conductor 23, relay coil 15 is connected in series with the lamp and is energized, causing switches 13 and 14 to open, the opening of switch 13 firing the lamp if it is in good condition. Coil 15 remains energized due to current flow through the lamp. Heater 18 is practically shortcircuited intermittently during this starting action by switch 13 and after the lamp has fired heater 18 is subjected to substantially the lamp operating voltage, which does not cause sulficient heat to be developed in this heater to prevent the thermal element 24 from cooling and returning to its normal downwardly closed position ready for a subsequent restarting action. Switch 14 being open prevents the closing of thermal element 24 in its "downwardly closed position from reclosing the circuit around the relay coil 15.

If the lamp does not fire, however, the lamp will flash intermittently due to the movement of thermal switch member 24 into and out of contact with conductor 23. During the part of the flashing cycle when element 24 is out of contact with conductor 23 heater 18 is subjected to substantially the open circuit voltage of reactor transformer 7 which is higher than the operating voltage of the lamp and consequently causes greater heat development in heater 18. While the lamp is flashing and the relay is opening and closing, such heat development from heater 13, plus that from heater 16, will cause the thermal element 24 to move to its upwardly closed position in which it engages contact 22. Current will then be supplied from conductor 11 through conductors 17 and 19, through the reactor 'or resistor 21 and starter contacts 22 and thermal element 24, and through starter heater 16 and conductor 15' to the relay coil 15, which current will be sufficient to heat up heater 16 so that it, together with the heat supplied by heater 13, will keep the thermal element 24 in engagement with contact 22, which keeps the relay energized, and the starter locked out of normal starting position, This position will be maintained to interrupt the starting action until the defective lamp is replaced.

A glow lamp 26 can be used if desired across the reactor or resistor 21 to indicate a defective fluorescent lamp. There will be a delay, however, waiting for the heaters 16 and 18 to cool oil 'sufliciently to permit starter contact 24 to return to its downwardly closed position, before a new lamp can restart. This time delay can be avoided by replacing the starter at the same time as the lamp. The new starter being cold will immediately initiate a lamp starting action, provided the line circuit is closed, and the starter removed can be used later with another lamp, as it will not have been damaged in any way. The starter of this circuit requires only four leads.

The circuit organization shown in Fig. 2 is the same as that shown in Fig. 1 with respect to the arrangement of parts 1 to 11 inclusive, 13, 14, '15, 2t), '21, 23, 24, and 26, but differs therefrom in that the heater 16 is connected in conductor 12 between relay switch 13 and filament 3, and heater 18 is disposed in the con? ductor 19 in series with the reactor or resistor 21, and the conductor 17 is dispensed with. On starting, current flows from the secondary 8 of reactor-transformer 7 through filament 2, conductor 11, relay switch 13, conductor 12, and heater 16 to and through filament 3 and conductor 25 to the thermal element 24 in its downwardly closed position and through conductor 23, relay switch 14 and conductor 20 to the line at 5. When thermal element 24 has been heated sufliciently, it will move out of engagement with conductor 23 and break the short circuit around the relay coil 15 and the relay coil 15 will be energized to cause the relay to open the switches 13 and 14. When switch 13 opens, the lamp, if in good order, will fire and as long as the lamp is in operation coil 15 will be energized to keep the switches 13 and 14 open, and maintain the operating circuit through the gaseous lamp 1. Thermal element 24 then returns to its downwardly closed position ready for another restarting action.

In case the lamp fails to fire, however, the relay will open and close and additional heat will be supplied to heater 16. When this has continued for a certain period of time, the thermal element 24 will move to its upwardly closed position, in engagement with contact 22, and thus cut in the heater 18 and reactor or resistor 21. The heat from heater 18 will cause thermal element 24 to stay closed in its upwardly closed position in contact with contact 22 and suflicient current will be supplied through this connection to keep the relay coil energized to hold its switches open. The starter will thus be locked out of action in the manner previously described until the defective lamp is replaced by a good lamp.

As with the circuit shown in Fig. 1, however, some delay will occur before thermal element 24 will return to its downwardly closed position. On the application of a new lamp and starter and reapplication of line current the starter will be ready to initiate a starting action again. The starter removed can be used later with another lamp as it will not have been damaged in any way. This starter requires the use of five leads.

Referring now more particularly to the form of the invention shown in Fig. 3, 1 represents the gas containing envelope of the lamp having the filamentary electrodes 2 and 3, and 4 and 5 are line circuit conductors for supplying current from a suitable A. C. source to the lamp and starter elements located in the can or casing10. These conductors are connected at the terminals B, W to the terminal leads of the primary 6 of a reactor-transformer 7, which is thus connected across the line. From the secondary 8 of this reactor-transformer leads a feed conductor 9 which is connected to one end of the filament 2, from the other end of which extends a preheating or return conductor 11 formed of branches 11, 12, 17, the branches 11 and 12 being coupled'by the normally closed automatically reclosing switch member 13 of a relay, ineluding a second switch member 14, and an actuating coil 15 arranged in the conductor 15'. A condenser 13 is placed across the switch member 13 to prevent arcing at the contacts when said switch member opens.

The branch 12 leads from switch member 13 to the input end of the filament 3 and has arranged therein a heater 16 which is connected in series with the filament 3. A second conductor 17 is connected to the conductor branches 11, 11' and by-passes the switch 13 and has arranged therein .a second or auxiliary heater 18, which is thereby connected across the switch 13. Heater 18 is electrically insulated from heater 16 except at their common junction point and is of high resistance compared with heater 16. Conductors 9, 11, 11' and 12 form parts of a preheating circuit for preheating the filaments. Conductors 9, 11 and 17 form parts of a second circuit which is short-circuited by the switch 13 when the latter is closed, and is set into action when the switch 13 opens to break the preheating circuit.

Conductors 19 and 20 are connected respectively at one end to the conductor '17 and to the line terminal 5.

Conductor 19 has arranged therein a reactor or resistor 21 and terminates at its opposite end in a contact 22. Conductor 20 is connected at its opposite end through the relay switch 14, conductor 23, thermal element 24 and conductor 25 with the output end of the filament 3. Switch 14 normally connects the conductors 20 and 23, and thermal element 24 in its downwardly closed position normally connects conductors 23 and 25 to complete the preheating circuit through conductors 11 and 12 until thermal element 24 moves out of engagement with conductor 23 due to heat from heater 16. Relay coil is arranged in the shunt conductor 15' connected across thermal element 24 and relay switch 14 and between conductors and so that the coil is short circuited as long as the thermal element 24 is closed in its downwardly closed position to connect conductors 23, 25.

Thermal element 24 is adapted when heated to a certaindegree or for a certain period of time to break connection between conductors 23 and 25 without engaging contact 22, thus connecting coil 15 into the preheating circuit so that it will be energized and open both of its switches 13 and 14. When thermal element 24 is heated to a greater extent or for a sufiicient time to cause it to engage contact 22 it will connect coil 15 through conductors 17, 19 and 20 and reactor or resistor 21 with line conductor 5, thus causing the relay to remain in the position in which its switches 13 and 14 are open. The thermal element 24 is one which is relatively slow moving to the full open position and opens to different degrees under different degrees of heat to perform the functions described. A glow or other type of lamp 26 may, if desired, be connected across the reactor or resistor 21 to indicate that the fluorescent lamp is defective. The current passed by reactor or resistor 21, while sufficient to hold the relay in the above described position, is not enough to cause filament 2 to glow.

When starting, current flows from line conductor 4 to and through the primary 6 of the reactor-transformer 7 to conductor 5, and also to and through the secondary 8 of the reactor-transformer 7 and conductor 9 to and through filament 2, relay switch 13, heater element 16, filament 3, through thermal element 24 closed in its downwardly closed position and through the closed relay switch 14 to line conductor 5. During the time the filaments and heater 16 are being heated, heater 18 is short circuited by switch 13 and plays no part in the action. When the heat supplied to heater 16 has been applied long enough to cause the thermal element 24 to move out of engagement with conductor 23 and break the circuit between conductors 23 and 25, the relay coil 15 is connected in series with the lamp and is energized, causing the relay switch 13 to open the preheating circuit and the lamp, if in good order, to fire, and also causing relay switch 14 to open and remove the short circuit around the coil 15 so that the coil can remain energized when the thermal element 24 cools off and returns to its normal downwardly closed position.

If the lamp fires normally, heat is no longer developed in heater element 16 to move the thermal element 24 out of its normal downwardly closed position, as this heater is cut out of circuit automatically by the firing of the lamp. Some heat is developed in heater 18, as this is connected across the lamp voltage as soon as the lamp fires. However, this is not enough to cause thermal element 24 to move out of its normal downwardly closed position. Hence the lamp will operate in the usual manner and, in the event that it is turned ofi and shortly thereafter is again turned on, it will rapidly refire because the thermal element 24 will be in its downwardly closed position ready to restart the lamp.

If, however, the lamp should fail to fire after one or more attempts, due to a defect or to the fact that it has reached the end of its useful life, then, when switch 13 opens a higher voltage is impressed across the auxiliary heater 18, and even though the relay may be repeatedly opening and closing, this combined heat applied to both heaters 16 and 18 at the same time, will cause thermal element 24 to have a greater amplitude of movement upward, so that it will close in its upward position in engagement with contact 22 of conductor 19. In that position' of the thermal element 24 current will flow from conductor 11 through conductors 17 and 19 through the reactor or resistor 21 and through contact 22, through thermal element 24 and relay coil 15 to line conductor 5. A by-pass holding circuit is thus established which feeds sufiicient current to the relay coil 15 to keep the relay switches 13 and 14 open but this current does not pass enough current to cause filament 2 to glow.

The characteristics of the reactor-transformer 7 are such that under this condition more than normal operating lamp voltage is impressed on heater element 18 which is of sufiicient capacity to keep the thermal element 24 in its upwardly closed position, whereby it is kept from reclosing its contact in its downwardly closed position and attempting to restart the lamp. At the same time, glow lamp 26 (if used) will glow to indicate that the fluorescent lamp is defective. Thus when a defective lamp flashes, the operation of the thermostatic starter itself will be such as to move thermal element 24 from the normal starting position to one in Which it feeds current to energize the relay coil to prevent further starting impulses, and the starter will be held in this position by the excess voltage supplied to the auxiliary heater 18. Repeated fiashings and movements of the starter and relay switches are thus prevented to avoid these objections and injury to such parts and the electrodes of the lamp.

On removal of the defective lamp and its replacement with a new lamp, thermal element 24 and relay will automatically return to their normal positions, but a delay of several minutes may be involved. This may be avoided by removing the starter and replacing it with a new one at the same time the lamp is replaced. The new lamp will then fire promptly and the starter so removed may be used later with another lamp, as it will not have been damaged in any way. By employing a thermostatically actuated starter which in conjunction with a relay permits these two functions to be obtained, the use of any additional means in conjunction with the starter and controlling relay to perform such functions is avoided and the starting means simplified to such extent. This circuit arrangement allows action of thermal element 24 to give the lamp a number of opportunities to fire before the starter and lamp are locked out. The intermittent closing and opening of relay contacts 13 during this period will help to call attention to the defective fluorescent lamp, prior to the time it is locked out. This starter requires the use of six leads.

Fig. 4 shows a circuit similar to Fig. 3 except that a reactor ballast 7, arranged in'conductor 9, is employed instead of a reactor-transformer, the invention being applicable for use in connection with lamp circuits employing a reactor of this type. The operation of this circuit is the same as that described with respect to Fig. 3. The starter in this circuit requires the use of six leads.

in the circuits shown in Figs. 1, 2 3 and 4 the holding circuit for the relay in the locked out position of the starter is purposely connected to one side of the filament at the high voltage end of the lamp as shown. This connection prevents conduction of current through the gas in the lamp at low current values in the locked out position of the starter, which occurs with some defective lamps if the connection is made to terminal B instead. This low current operation or ghost lighting is usually flickering and very objectionable. This ghost lighting occurs usually only with lamps with reactor-transformers, such as shown in Figs. 1, 2 and 3 which increase the lamp voltage above the line voltage and does not occur on D. C. It might not occur in the circuit shown in Fig. 4, without this provision, depending on the line voltage and size of lamp used.

Figs. 5 and 7 show circuit arrangements having the starter lockout feature and designed for 'use in connection with a source of supply of D. C. current. While Figs. 6, 8 and 9 show similar arrangements designed for operation on either an A. C. or D. C. source of current supply.

In Fig. 5, 1 is the fluorescent lamp having the electrodes 2, 3, and 4, 5' are line conductors for supplying D. C. current from a suitable source of supply to the lamp and starter elements located in the starter can or casing To conductor 4' is connected the section 9 of a preheating conductor including a section 9* leading to the filament 2' and containing a heater 16 and a current limiting resistor 8 Conductor section 9 contains a reactor 21 and the conductor sections 9 and W are normally connected by a relay switch or set of contacts 13* ior supplying preheating current to the filament 2' when the line circuit is closed. A condenser 13 is placed across this switch to prevent arcing at its contacts when the switchv opens.

Filament 2' is connected to the conductor 5' by a return conductor comprising sections 11 and 11 between which is arranged the relay coil 115 while filament 3, is connected to the conductor section 9 between the reactor and the switch 13*, by the operating conductor 15' in which is arranged a ballast lamp 26*. across the coil 15 between conductor sections 11 11 is a control circuit comprising connections leading from said conductor sections and an intermediate conne ction 23 said connections being spaced to provide gaps therebetween. normally close the gap between the branches 28 23 and a normally closed thermal element 24 is provided to close the gap between the branches 23 25 to normally complete the control circuit to initiate a preheating action, in which the filament 2 and heater 16 are heated,

when the line circuit is closed to start the lamp.

A normally open lock-out circuit is also provided which comprises a conductor 19 connected at one. end to conductor 15 and having a contact 22 at its opposite end arranged to be engaged by the thermal element 24 on an abnormal or extended upward movement of the latter. The conductor 19 has arranged therein a current limiting resistor 8 and a heater 18 The heaters 16 18 are electrically insulated from each other and are provided to heat the thermal element 24:". This thermal element 2.4 like the element 24 prevously described, has lower and upper contacts between which it is movable when heated: to make and break the control circuit, which forms part of the preheating circuit, and make and break the lock-out circuit, and said thermal element is arranged to be cut out of the circuit by the action of the relay when the lamp is operating, normally.

In this circuit of Fig. 5 when starting, preheating current flows. from the positive side 4 of the line, through the reactor 21*, through normally closed contacts 13 L of: the relay, through resistor 8 through heater 16 of the starter, through the negative filament 2' of the fluorescent lamp, back through thermal element 24 of the starter in its, downwardly closed position, through con.- tacts 14 of the relay, and thence to the negative side of the line 5'. A circuit is also established from the low side of the reactor 21 through conductor 15* through the ballast lamp. 26 to the positive filament of the lamp. Initially the contact 24 of the starter, together with the contacts 14 of the relay shortcircuit the relay coil 15, so that it cannot be energized.

When current has flowed for a long enough time to heat the'heater 16 sufliciently to cause thermal element 24 to move out of its downwardly closed position, which is presumed-to be long enough to heat the lamp sufiiciently to fire, then thermal element 24* opens the short circuit around the coil 15 of'the relay, causing it to be energized and open its contacts 13 and' 14*. Opening of contacts 13 fires the lamp, if in good condition, and openingof contacts 14 prevents thermal element 24 from short Connected A relay switch 14 is provided to til circuiting the relay coil 15 when it returns to its downwardly closed position. The opening of relay contacts 13 removes the current from the heater 16 of the starter so that thermal element 24 will return to its downwardly closed position very shortly after the lamp fires.

While the lamp is operating normally, current flows from the positive side of the line through the reactor 21*, through the conductor 15 and ballast lamp 26 to the positive filament 3 of the lamp, through the gas of the lamp itself, and from the negative filament 2' of the lamp, through the coil 15 of the relay back to the negative side of the line.

Should the line circuit be interrupted, the relay immediately drops out and the circuit is ready to commence another starting action as soon as the line circuit is reclosed.

If the lamp does not fire, however, the starting cycle will be repeated a number of times increasing the heat in heater 16 each time until it is sufiicient to cause thermal element 24 to move to its upwardly closed position in contact with contact 22*. In this position it closes 'a circuit from the positive side of the line, through the reactor 21 through conductor 19 and resistor 8*, through heater 18 through thermal element 24 of the starter and through the coil 15 of the relay, to the negative side of the line, thus keeping the relay energized, its contacts 13 and 14 open, and keeping all current off the fluorescent lamp as well as stopping all efforts to restart it.

If the line circuit is opened and then reclosed, the same starting attempts will be repeated until thermal element 24 of the starter closes in its upwardly closed position in contact with contact 22 closing the circuit through resistor 8 and heater 1% to hold the relay open continuously. Heater l8 would be of sufficient capacity to insure that thermal element 24 will remain in its upwardly closed position. Some delay will be encountered in the return of contact 24 to its downwardly closed position after a cut-out action has occurred, but this can be eliminated by changing the starter as described with respect to the circuits shown in Figs. 3 and 4. The starter in this circuit Fig. 5 requires the use of five leads.

Fig. 6 shows a circuit arrangement suitable for operation of lamps on either A. C. or D. C. and employing conductor sections 9, 9 respectively connected with line conductor 4' and filament 2', and a conductor section 9 arranged between conductor section 9 and one end of the filament 3. Conductor section 9 contains the reactor 21 and has connected therewith the operating conductor 15 which contains the relay coil 15 and ballast lamp 26 and which leads thereto from the other end of the filament 3. In conductor 9 is arranged the heater 16 and between conductors 9 and 9 is arranged the relay switch 13, which normally connects said conductors and across the terminals of which is placed the arc suppressing condenser 13.

A preheating and control conductor comprising branches 20, 20, 20 is provided for connection with conductor sections 9, 9' through the filament 3' to conmeet the filaments 2" and 3' in series for a preheating action. A normally closed relay switch 14 connects conductors Zfi and 9 with conductor 20 and a thermal element 24 normally connects conductor sections 20, 20 so that when the switches 14, 24 and 13 are in their normal positions or closed, preheating current is supplied to the filaments upon closing the line circuit. It will be observed that the conductors 29* 20, 20 form when closed a circuit which lay-passes and short circuits the conductor 15 relay coil 15, and ballast lamp 26. A normally open lock-out conductor 19? is connectedat one end with the conductor 11 and contains a current limiting reactor or resistor 8 A second heater 18 in.-. sulated from the heater 16, has a contact 22 at its opposite end arranged to be engaged by the thermal element 24 to close said conductor to establish the lock-out circuit.

In this circuit, when starting, current flows from one side 4 of the line through the reactor 21*, through normally closed contacts 14 of the relay through conductor 20, through thermal element 24 of the starter in its downwardly closed position, through filament 3 of the fluorescent lamp, through heater 16 of the starter, through normally closed contacts 13 of the relay, through resistor 8, through filament 2 of the fluorescent lamp and back through conductor 11 to the other side of the line. A circuit is also established from conductor 9 through the coil 15 of the relay, through the ballast lamp 26 to the filament 3' of the fluorescent lamp. Initially the relay coil 15 and the ballast lamp 26 are short circuited by the thermal element 24 of the starter and relay contacts 140, so that the relay coil cannot be energized to operate the relay.

Current continues to flow through the above described circuit until heater 16 of the starter heats up sufiiciently to cause thermal element 24 to move out of its downwardly closed position. When it does, the short circuit around coil 15 and the ballast lamp 26 is removed and the relay coil 15 is energized causing it to open contacts 13 and 14. Opening of contacts 13 fires the lamp, if in good condition, while the opening of contacts 14 insures that the short circuit will not be re-established across the relay coil 15 when thermal element 24 returns to its downwardly closed position.

If the lamp fires normally, current flows from the line terminal 4 through the reactor 21, through the coil 15 of the relay, the ballast lamp 26*, the filament 3 of the fluorescent lamp through the gas in the lamp to the filament 2 and back to the other line terminal 5.

Should the line circuit be interrupted, the relay coil is immediately deenergized causing the contacts 13 and 14 to return to their closed position and the circuit is ready to commence another starting action as soon as the line circuit is reclosed.

If, however, the lamp fails to fire at the first attempt, it will make successive attempts to do so, each one building up more heat in the heater 16 of the starter, until sufiicient heat is built up to cause thermal element 24 to move to its upwardly closed position in contact with contact 22". In this position, a circuit is established from the line terminal 4 through the reactor 21*, through the coil 15 the ballast lamp 26 thermal element 24 of the starter, heater 18 resistor 8 to the other line terminal 5'. Heater 18 would be of sutficient capacity to keep thermal element 24 closed in its upwardly closed position in contact with contact 22 As long as this occurs, the relay coil remains energized, the contacts 13 and 14 open and the lamp is held entirely out of the circuit so long as the line circuit remains closed.

If the starter goes into the locked out condition some time is required for its return to normal starting position. This can be avoided by removing both the lamp and the starter and installing a new starter as described with respect to the circuit shown in Fig. 1 and the starter removed can be used later with another lamp, as it will not have been damaged in any way.

The starter of Fig. 6 requires the use of five leads.

Fig. 7 shows a D. C. circuit with a multiple action lockout starter having two heaters 16 and 18*. Heater 16 is used in normal starting, while heater 18 is used to provide the lock-out action. This circuit includes the preheating conductor 9 containing the reactor 21 the relay switch 1 0 20 connected at one end to conductor 15 oh the line side of the ballast lamp and having at its opposite or free end the fixed starter contact 22 Switches 113 and 14 are normally closed and thermal element 24 is normally closed in its downwardly closed position shown, in which it engages the lower contact 22 but it is movable slowly upwardly under the action of heat supplied by heaters 16 and 18 to a position to engage its upper stationary contact 22 to break the shunt circuit through conductor 25 and close the holding circuit through conductor 20.

In starting, current flows from the positive side of the line 4 to and through the preheating conductor 9 and switch 13 of the relay, heater 16 and current limiting resistor 8 arranged therein, through the negative filament 2 of the lamp, back through conductor 11 and thermal element 24, in its downwardly closed position, relay switch 14 in its closed position and thence to the negative side of the line. It will be noted that thermal element 24 and switch contacts 14 short circuit the coil 15 of the relay at this time and prevent the coil 15 from being energized.

Current continues to flow until heater 16 heats up sufficiently to cause thermal element 24 to move out of its downwardly closedposition. When this occurs, the coil 15 of the relay is cut into the preheating circuit and energized and opens switches 13 and 14 Opening of switch 13 gives an inductive kick to fire the lamp, through the operating circuit from the reactor, through the ballast lamp to the positive filament of the lamp.

The lamp if in normal condition fires, holding the relay coil 15 energized and keeping relay switches 13 and 14 open. Current then flows through the reactor, through the ballast lamp to the positive filament, through the gas in the lamp to the negative filament and thence back to the negative side of the line through the relay coil 15. The thermal element 24 then returns to its downwardly closed position without any eflect, since relay switch 14 remains open.

A secondary circuit is established from the lamp side of the ballast lamp, through conductor 19, and heater 18 to the negative filament of the lamp. This places lamp voltage across heater 18 which does not cause enough heat to be generated to affect the operation of thermal element 24 or prevent its return to its normally downwardly closed position. The lamp continues to operate in this manner, and if the line circuit is opened the starter is ready to commence another restarting action immediately, since thermal element 24 is closed in its downwardly closed position and the relay contacts 13 and 14 close immediately upon opening of the line circuit.

Should the lamp fail to fire, however, the starter will make several attempts to start it. Each time that switch 13 is opened, substantially line voltage is impressed across heater 18 which is of very high resistance compared to that of heater 16 The accumulative effect of the heat generated in heaters 16 and 18 during these attempted starts, finally moves thermal element 24 to its upwardly closed position. In this position a circuit is established from the positive side of the line, through the reactor, through resistor 8 through thermal element 24, back through the coil 15 of the relay to the negative side of the line. This current holds the relay coil energized and holds switches 13 and 14 open and stops further attempts to start the lamp. A circuit is also established from the positive side of the line through the reactor, through the ballast lamp, the heater 18 resistor 8*, the negative filament of the lamp, the coil 15 and back to the negative side of the line. This keeps substantially line voltage applied to heater 18 which ensures that thermal element 24 will remain in its upwardly closed position.

Some delay (several minutes), will be involved before thermal element 24 returns to its downwardly closed position after this condition of lockout, but this can be 1 I avoided by changing both the lamp and starter, as described with reference to Fig. 1. The starter removed can be used later with some other lamp, as it will not have been damaged in any way. The starter in this circuit requires the use of six leads.

The circuit shown in Fig. 8 comprises a feed conductor leading from line terminal 4 and including a section 9 containing a reactor 21, a section 9 having gaps normally closed by a relay switch 14 and a thermal element 24 a section 9 connected with one terminal of filament 3 and a section 9* containing the heater 16 and current limiting resistor 8 and connected to one terminal of the filament 2 from the opposite terminal of which return conductor if leads to line terminal 5. A second heater 18 is arranged in a branch connection between conductor sections Q and 9 so as to be heated in a manner hereinafter described. Connected between conductor sec tions 9 and 9*, in shunt with conductor section 9 when the latter is closed by switches 14 and 24- is a conductor 15 containing the relay coil 15 and the ballast lamp 26 The conductors as thus arranged provide starting and operating circuits including both filaments of the lamp which are normally connected in series for a preheating action, in the normal position of the parts shown, and upon the line circuit being closed. Another conductor 20 connected at one end with the conductor 11* and containing a current limiting resistor 8 and provided at its opposite end with a switch contact 22 arranged above the thermal element contact 22 in conductor section 9 is employed to complete a circuit for a lock-out action, if the lamp is defective. Reference characters x, x and y, y, y denote the starter terminals to which the conductors are connected. While this circuit is shown as employing a reactor 21 a reactor-transformer may be employed in place of the reactor as, for example, in the circuit shown in Fig. 3 if the circuit is used on A. C.

in this circuit in starting, current flows from one side of the line through the reactor and through relay switch 14 to terminal y of the starter, through the thermal element 2 closed in its downwardly closed position, to terminal x, thence to and through filament 3 of the fluorescent lamp, through the closed relay switch 13 to terminal y, through the heater 16 the current limiting resistor 8 and through filament 2 of the fluorescent t lamp, to the other side of the line. Under this condition, the switch 14 and thermal element 24: short circuit the relay coil 15 and the ballast lamp 26. Heater 16 is of relatively low resistance, while heater 18 is of high resistance and is effectively short circuited at this time.

Preheating current continues to flow until the filaments of the fluorescent lamp are properly heated, when heater 16 causes thermal element 24 to move out of its downwardly closed position. When this occurs, it breaks the short circuit around the ballast lamp 26 and coil 15 of the relay, so that the relay coil is energized and causes switches 13 and 14 to open. Switch 13 an opening, breaks the inductive circuit through the reactor and the filaments of the fluorescent lamp and causes the. lamp, if in normal condition, to fire. Switch 14 being open, prevents the short circuit from being re-established around the ballast lamp and coil of the relay, when thermal element 24* returns to its normal downwardly closed position. Current flowing through the lamp keeps coil 15 energized and switch contacts 13 and 14 open.

The operating circuit is from one side of the line through the reactor, through the coil 15 of the relay, through the ballast lamp 26 to one filament of the fluorescent lamp, through the gas in the lamp itself, to the other filament, and back to the other side of the line. During this action, heater 18' has lamp voltage impressed across it, which does not generate enough heat to cause it to move thermal element 24 out of its downwardly closed position to which it returns when heater 16 cools on.

After the lamp has operated normally for a few sec-. ond's, if the line circuit is opened, the relay coil is deenergiz'ed and switches 13 and 14 return immediately to their normally closed position as shown, in which they, together with thermal element 24 closed in its downwardly closed position, are ready for another starting action, as soon as the line circuit is reclosed.

If, however, the lamp fails to fire on the first attempt, the starter will make a number of other attempts to start it, and each time the contacts of switch 13 are opened with the lamp not having fired, substantially line voltage is applied across heater 18 This generates sufficient heat in time to cause it in conjunction with heater 16 to move thermal element 24 into engagement with contact 22 in its upwardly closed position. In this position thermal element 24 closes the circuit from one side of the line, through the reactor, through the relay coil 15 through the ballast lamp 26 to terminal x of the starter, through thermal element 24 in its upwardly closed position to terminal y of the starter, through reactor or resistor 8 and thence to the other side of the line.

Reactor or resistor 8 passes enough current to keep the relay coil energized, thus holding switches 13 and 14 open. Under this condition, the fluorescent lamp is cut out of the circuit. There would be sufficient current flow through the relay coil 15 and reactor or resistor 8 to prevent current flow at low values or ghost lighting in the longer sizes of A. C. lamps, but not enough to cause filament 2 to glow. I

In common with all other circuits having the multiple action lock-out feature, there will bean appreciable time delay (several minutes) if the defective fluorescent lamp is replaced, before heater 18 cools off sufliciently to allow thermal element 24 to return to its downwardly closed position to start the lamp. This time delay can be avoided however, by replacing the defective fluorescent lamp and the starter at the same time. The starter can then be used later in some other circuit as it will not have been injured in any way. The starter in this circuit has five terminal leads.

Fig. 9 shows a similar circuit especially designed for cold starting conditions and with the lock-out feature. This circuit comprises a feed conductor 9 containing a reactor 21 and leading from the line terminal 4 to the input terminal oi the filament 2 from the other terminal of which extends a return conductor comprising a section 11 leading from the output terminal of filament 2 to the input terminal of filament 3, a conductor section 11" connected to the output terminal of filament 3 a conductor section 11 connected to the line terminal 5, and a conductor section 211 arranged between the conductor sections 11* and 11. I

Conductor section 11 contains a current limiting resistor 8 and has a gap normally closed by a relay switch 13, while conductor section 11 has two gaps, one normally closed by a relay switch 14, and the other by a thermal element 24 normally engaging in its lower position a contact 22 and movable when heated to engage a contact 22 at the adjacent end of a conductor 20 in which is a reactor or resistor 21 across which may be connected a glow lamp 26 which conductor 20 is connected at its opposite end to the conductor "11 between filament 2 and switch 13. in conductor l1 is a heater 16 and in a connection 28 between conductor 20 and a portion of the conductor 11 is a second heater 18 for heating the contact 24, which functions similar to the similar heaters and thermal elements before described. A conductor 15 is connected between conductors 11 119 across conductor 11, so as to be shunted when switch 14. is closed and thermal element 24 closed, in its downwardly closed position, and contains the relay coil 15, ballast lamp 26 and current limiting resistor 8.

The starter includes two heaters, the heater 16 being of low resistance for normal starting and the heater 18* of high resistance for the cut-.1 ut operation. The thermal element 24 moves relatively slowly between the upper and lower contacts 22 and 22 and in its upwardly closed position passes suflicient current through a reactor or resistor 21 to keep the relay coil energized, but this circuit does not pass enough current to cause the filament 2 of the lamp to glow. A glow lamp 26 may be connected across reactor or resistor 21 to indicate that the fluorescent lamp is defective.

In place of the reactor 21, a reactor-transformer may beused as in the circuit shown in Fig. 3 when the lamp is operated on A. C.

In this circuit, when starting, current flows from the line through the reactor 21, through filament 2 of the fluorescent lamp, through the normally closed contacts of the relay switch 13, through resistor 8 to terminal x of the starter, through heater 16 to terminal y of the starter, through the other filament 3 of the fluorescent lamp to terminal y of the starter, through thermal element 24 in its downwardly closed position to terminal of the starter, and through the normally closed contacts of the relay switch 14 to the other side of the line. In this condition the thermal element 24 and the switch 14 short circuit resistor 8, the ballast lamp 26 and the relay coil 15, thus preventing the coil from being energized and picking up the relay. Heater 18 is also efiectively short circuited at this time. The preheating current can be set at the proper value by selecting a suitable value for resistor 8.

Preheating current continues to flow until heater 16 heats up sufficiently to cause thermal element 24 to move out of its downwardly closed position. When this occurs, the short circuit around resistor 8, the ballast lamp 26 and relay coil 15 is removed. Current then flows through this circuit 15 energizing the relay coil 15, which in turn causes the relay to open switches 13 and 14. The opening of switch 13 breaks the preheating circuit and causes the reactor to give an inductive kick to fire the lamp. The lamp, if in normal condition fires,-and the relay coil remains energized by current flow through the lamp. This keeps the switches 13 and 14 open.

Switch 14 being open prevents thermal contact 24 from reclosing the short circuit around resistance 8, the ballast lamp 26 and the relay coil when the said thermal element 24 returns to normal position after heater 16 cools ofl.

After the lamp has fired, heater 18 has lamp voltage impressed across it, but this does not generate sufiicient heat to cause it to move the thermal element 24 out of its downwardly closed position.

The operating circuit is from the line terminal 4, through the reactor, through filament 2 of the fluorescent lamp, through the gas in the lamp itself to the other filament 3, thence through resistor 8, ballast lamp 26 and relay coil 15 to the other side of the line. Resistor 8 and ballast lamp 26 can be so chosen as to properly regulate the operating current.

If while the lamp is operating normally, the line circuit is opened, relay coil 15 is de-energized and relay switches 13 and 14 return to their closed positions immediately for another starting action. As long as the lamp has operated longer than the few seconds required for the thermal element 24 to return to its downwardly closed position, there is always a flow of current upon closing or reclosing the line circuit which causes the filaments to glow to show that the lamp is ready to start.

Should the lamp fail to start on the first attempt, the starter will make successive attempts to start it. Each time that relay switch 13 opens without the lamp firing, approximately line voltage is impressed across heater 18 Line voltage generates considerably more heat in heater 18 than lamp voltage and after a number of successive attempts heater 18 in conjunction with heater 16 Will 14 heat up enough to move thermal element 24 into its up wardly closed position. In this position thermal element 24 engages the contact 22 and establishes a circuit from the line terminal 4, through filament 2 of the fluorescent lamp, through the reactor or resistor 21 to terminal of the starter, through thermal element 24 to terminal y of the starter, through resistor 8, ballast lamp 26 and relay coil 15, back to the other side of the line 5. This keeps the relay coil energized, its contacts 13 and 14 open, and the lamp cut out. A glow lamp 26 can be connected to reactor or resistor across 21 if desired to indicate a defective lamp.

As in all circuits having the multiple action lockout feature, an appreciable time delay (several minutes) will be required when a defective lamp is replaced before the thermal element 24 will return to its downwardly closed position ready for another starting action. This time delay can be avoided, however, by replacing the defective lamp and the starter together. The starter can be used later in some other circuits as it will not have been damaged in any way.

By the use of reactor or resistor 21 as shown, current flow at low values, i. e., ghost lighting, is eliminated in long lamps when operating on A. C.

It will be observed that all the circuits equipped with the lockout arrangements herein disclosed have the advantage that the lockout feature in the case of a lamp that ,will not fire is automatic in its lockout action and is automatically reset, so that it is not necessary for a maintainer to push any button or other device in order to get the circuit back to normal. In each case it is only necessary to remove the lamp and probably the starter and to install a new lamp and starter to start illumination again, and the starter removed can be used with another lamp as it will not have been damaged in any way. In industrial applications where there are a large number of fixtures in rows and it is diflicult to reach portions of the fixtures other than the lamps and starters, this is of special advantage.

In all the circuits herein shown the starter automatically returns to normal position when the lamp begins to operate, so that if the lamp after a short interval is turned off and then is again turned on, the starter is ready to immediately commence another starting operation. This gives a distinct advantage over circuits using a straight thermal or glow switch type of starter in the use of which it is often necessary on closing the line circuit to Wait until the starter is in correct position for firing.

In the use of my circuits herein disclosed it is only necessary in the case of a defective lamp to wait until the starter cools off for a restart after the lamp has been replaced, or replace the starter, which, however, is not of particular consequence. By the provision of means of the character described for locking out the starter automatically when a defective or burned out lamp is in use the disadvantages hereinbefore set forth encountered in the use of ordinary circuits subject thereto are overcome in a simple and effective manner.

Furthermore, as in the case of my previous applications, when the lamp is operating normally a glow is always present immediately in at least one filament to indicate that the starting circuit is complete, upon closing the line switch.

Practical use of the starter organizations herein disclosed has shown that the starter relay circuits work with greater efiiciency than ordinary starters, and will fire-lamps which glow switch starters and other thermostatic starters will not fire, due to the rapid breaking of the preheating circuit by the relay contacts which is much more rapid than is obtained by any of the starters now generally employed. This prevents the troubles and annoyances often caused in starting lamps, particularly those of the type described, in using the glow switch type of starter and other starters.

In all the circuits herein shown there is provided a thermpstatic starter having a thermal element which will move from one position to another if sutficient heat is applied to it, but when the lamp is operating normally, the thermal element will return to its downwardly closed position, so that if the lamp is turned off and then turned on again immediately, the starter is ready to immediately commence another starting operation. This gives a dis-, tinct advantage over the straight thermal or glow switch type of starter, because a glow always occurs in the lamp immediately upon closing the line circuit, or upon reclosing it, with the possible exception, in circuits 5 and 6, of those lamps that will not fire.

It will be understood, of course, that while I have shown certain ways of carrying my invention into practical effect, other ways or means equivalent thereto, and falling within the scope of the appended claims, may be employed Without departing from the spirit of my invention. It will also be understood that while I have set forth the disadvantages of circuits using straight thermal and glow switch types of starters as hereinberore constructed and used, and the advantages attained by the use of a thermostatic type of starter, I do not limit myself to the use, except when specified in the claims, to any particular type of starter or time delay device which may be used to carry my invention into practical effect.

What is claimed is:

1. A system for supplying preheating and operating current to a discharge device comprising the combination of a supply line, a gaseous electric discharge device having two electrodes constructed to receive preheating current, a relay switch havingtwo setsof normally closed contacts, means including an inductive reactance device and the operating coil of said relay switch for connecting said electrodes with said supply line, a time delay device having main and auxiliary heating elements and a thermally responsive member constructed to move slowly from engagement with a normally closed contact provided on said time delay device to engage a normally open contact on said device under the action of heat from at least one of said heating elements, an electrode preheating circuit capable of producing firing temperature electrode heating, said circuit being a series circuit extending from one side of a voltage source to the opposite side of said source and including said inductive reactance device, one

of said electrodes, the first set of relay switch contacts,

said main heating element, the other of said electrodes, and a shunt circuit around said relay switch operating coil, said shunt circuit. including in series connection said thermally responsive member and said normally closed contact and the second set of relay-switch contacts so that after line circuit isclosed said main heating elementjwill be energized and cause said thermally responsive member to move away from said normally closed contact and thus cause the energization of said relay switch operating coil and the consequent opening of said sets of relay switch contacts, the opening of the first set of contacts causing an inductive voltage kick across the electrodes to cause the dischargedevice to fire, the first set of said switch contacts being connected across the electrodes, and the opening of the second set of relay contacts maintaining said operating coil energized after the re-engagernent of the thermally responsive member with said normally closed contact, and, should the discharge device not fire, said member intermittently disengaging and engaging said contact until the heat from said main heating element moves the thermally responsive member againstsaid normally open contact thereby closing a circuit through said auxiliary heating element to hold said contact closed and maintain the discharge device locked out of operation by the opening of said first set of relay switchcontacts.

2. A system for supplying preheating and operating current to a discharge device comprising thedcombination of a supply line, agaseouselectric discharge device having two electrodes constructed to receive preheating Cir current, a relay switch having two sets of normally closed contacts, means including an inductive reactance device and the operating coil of said relay switch for connecting said electrodes with said supply line, a time delay device having main and auxiliary heating elements and a thermally responsive member constructed to move slowly from engagement with a normally closed contact provided on said time delay device to engage a normally open contact on said device under the action of heat from at least one of said heating elements, an electrode preheating circuit capable of producing firing temperature electrode heating, said circuit being a series circuit extending from one side of a voltage source to the opposite side of said source and including said inductive reactance device, one of said electrodes, the first set of relay switch contacts, said main heating element, the other of said electrodes, and a shunt circuit around said relay switch operating coil, said shunt circuit including in series connection said thermally responsive member and said normally closed contact and the second set of relay switch contacts so that after the line circuit is'closed said main heating element will be energized and will cause said thermally responsive member to move away from said normally closed contact and thus cause the energization of said relay switch operating coil. and the consequent opening of said sets of relay switch contacts, the opening of the first set of contacts causing an inductive voltage kick across the electrodes to causethe discharge device to fire, the first set of said switch contacts being connected across the electrodes, and the opening of the second set of relay contacts maintaining said operating coil energized after the re-engagement of the thermally re-. sponsive member with said normally closed contact, and, should the discharge device not fire, said member intermittently engaging and disengaging said contact until the heat from said main and auxiliary heating elements moves the thermally responsive member against said normally open contact, the auxiliary heating element being connected across said first set of switch contacts thereby, when said contacts are open, receiving substantially the voltage across said electrodes, the engagement of said normally open contact energizing the relay switch operating coil and thereby opening said first set of switch contacts so as to apply heat to said auxiliary heating element to hold the thermally responsive member against said normally open contact and maintain the discharge device locked out of operation.

3. A system for supplying preheating and operating current to a gaseous electric discharge device as claimed in claim 2 in which the main heating elementis connected in the shunt circuit around the relay switch operatingcoil instead of being connected the electrode preheating circuit so that both main and auxiliary heating elements cooperate in moving the temperature responsive member into engagement with its normally open contact and also cooperate in holding said member in this position.

4. A system for supplying preheating and operating current to a gaseous electric discharge device as claimed in claim 2 in which the inductive reactance device has a reactance value to permit the flow of; a high preheating current, such current being regulated by a current limiting resistance included in the electrode preheating circuit, and wherein a current limiting device is included in series connection with the relay switch operating coil to supplement the inductive reactance device in controlling the operating current of the discharge device, the shunt circuit being connected around said coil and current lirn; iting device, whereby the amount of the electrodepreheating current can be regulated to permit a high preheating current to be established duringv the starting period when the thermally responsive. member. is intermittently engaging and disengagingits normally closed Contact, e aidc t mi in de ans i sl l sd inthe operating coil circuit toreduce the operating current after the discharge device has fired.

5. A system for supplying preheating and operating current to a discharge device comprising the combination of a supply line, a gaseous electric discharge device having at least one electrode constructed to receive preheating current, a relay switch having two sets of normally closed contacts, one of said electrodes being connected to a terminal of said supply line through an inductive reactance device, a time delay device having main and auxiliary heating elements and a thermally responsive member constructed to move slowly from engagement with a normally closed contact provided on said time delay device to engage a normally open contact on said device under the action'of heat from at least one of said heating elements, an electrode preheating circuit capable of producing firing temperature electrode heating, said circuit being a series circuit extending from one side of a voltage source to the opposite side of said source and including said inductive reactance device, the first set of relay switch contacts, said main heating element, said electrode, a shunt circuit around said relay switch operating coil, said shunt circuit including in series connection said thermally responsive member and said normally closed contact and the second set of relay switch contacts so that after the line circuit is closed said main heating element will be energized and cause said thermally responsive member to move away from said normally closed contact and thus cause the energization of said relay switch operating coil and the consequent opening of said sets of relay switch contacts, the opening of the first set of contacts causing an inductive voltage kick across the electrodes to cause the discharge device to fire, the first set of said switch contacts being connected across the electrodes, and the opening of the second set of relay contacts maintaining said operating coil energized after the re-engagement of the thermally responsive member with said normally closed contact, and, should the discharge device not fire, said member intermittently engaging and disengaging said contact until the heat from said main heating element moves the thermally responsive member against said normally open contact thereby closing a circuit through said auxiliary heating element, the heat from both said heating elements holding said contact closed and maintaining the discharge device locked out of operation by the opening of said first relay switch contacts.

6. A system for supplying preheating and operating current to a gaseous electric discharge device as claimed in claim in which the auxiliary heating element is connected to receive substantially the voltage across the electrodes, and the engagement of the thermally responsive member with its normally open contact closes a circuit which energizes the relay switch operating coil, the resulting opening of said first set of switch contacts causing said voltage to be applied to the auxiliary heating element which supplies heat to hold the thermally responsive member against its normally open contact to maintain the discharge device locked out of operation.

7. A system for supplying preheating and operating current to a discharge device comprising the combination of a supply line, a gaseous electric discharge device having two electrodes constructed to receive preheating current, a relay switch having two sets of normally closed contacts, means including an inductive reactance device and the operating coil of said relay switch for connecting said electrodes to the supply line, a time delay device having main and auxiliary heating elements and a thermally responsive member constructed to move slowly from engagement with a normally closed contact provided on said time delay device to engage a normally open contact on said device under the action of heat from at least one of said heating elements, an electrode preheating circuit capable of producing firing temperature electrode heating, said circuit being a series circuit extending from one side of a voltage source to the opposite side of said source and including said inductive reactance device, a shunt circuit around said operating coil,

one of said electrodes, said main heating element, the other set of relay switch contacts, and the first electrode,

said shunt circuit including in series connection said' thermally responsive member and said normally closed contact and the second set of relay switch contacts so that after the line circuit is closed said main heating element will cause said thermally responsive member to move away from said normally closed contact and thus cause the energization of said relay switch operating coil and the consequent opening of said sets of relay switch contacts, the opening of the first set of contacts causing an inductive voltage kick across the'electrodes to cause the discharge device to fire, the first set of said contacts being connected substantially across the electrodes, and the opening of the second set of relay contacts maintaining said operating coil energized after the re-engagement of the thermally responsive member with said normally closed contact, and, should the discharge device not fire, said member intermittently engaging and disengaging said contact until the heat from said main heating element moves the thermally responsive member against said normally open contact thereby closing a circuit which connects said auxiliary heating element across the electrodes, the heat from said heating element holding said contact closed and maintaining the discharge device locked out of operation by the opening of said first relay switch contacts.

8. A system for supplying preheating and operating current to a discharge device comprising the combination of a supply line, a gaseous electric discharge device having two electrodes constructed to receive preheating current, a relay switch having two sets of normally closed contacts, means including an inductive reactance device and the operating coil of said relay switch for connecting said electrodes with said supply line, a time delay device having a normally closed contact, a normally open contact and a thermally responsive member constructed to move slowly from engagement with said normally closed contact to engage said normally open contact, electrical resistance means for heating said thermally responsive member, an electrode preheating circuit capable of producing firing temperature electrode heating, said circuit being a series circuit extending from one side of a voltage source to the opposite side of said source and including said inductive reactance device, one of said electrodes, the first set of relay switch contacts, said heating means, and a shunt circuit around said relay switch operating coil, said shunt circuit including in series connection said thermally responsive member and said normally closed contact and the second set of relay switch contacts so that after the line circuit is closed said heating means will be energized and will cause said thermally responsive member to move away from said normally closed contact and thus cause the energization of said relay switch operating coil and the consequent opening of said sets of relay switch contacts, the opening of the first set of contacts causing an inductive voltage kick across the electrodes to cause the discharge device to fire, the first set of said switch contacts being connected across the electrodes, the opening of the second set of relay contacts maintaining said operating coil energized after the re-engagement of the thermally responsive member with said normally closed contact, and, should the discharge device not fire, said member intermittently engaging and disengaging said contact until the heat from said heating means causes the thermally responsive member to move against said normally open contact, thus energizing the relay switch operating coil to thereby maintain the discharge device locked out of operation.

Van Wijk July 7, 1936 Babb Feb. 15, 1944 

